An on-board power supply, also known as the power inverter, is a power converting device applied to the vehicle. The power converting device uses plurality of power devices to convert the external power into AC power or DC power. When the power converting device is in operation, the plurality of power devices can produce a large amount of heat. For avoiding the accumulated heat to influence the performance of the power converting device, it is desired to provide an effective thermal design for dissipating the heat generated from the power devices. Generally, the power devices which are through-hole devices and are soldered on a printed circuit board in a row. Then, the power devices are pressed to attach to the heat-dissipating housing, so as to ensure that the on-board power supply can be operated safely and reliably.
The power devices of a conventional on-board power supply are pressed to attach to the heat-dissipating housing closely by locking the screws which directly pass through the screw holes of the power devices into the heat-dissipating housing. The conventional on-board power supply employs a lot of power devices which are intensively placed together. If the power devices are mounted on the heat-dissipating housing by locking the screws which directly pass through the screw holes of the power devices into the heat-dissipating housing, it will use up manpower of large quantity and damage the power devices easily to result in serious malfunction of the on-board power supply. In addition, when the power devices are directly clamped to the heat-dissipating housing by the resilient steel sheet, the power density of the on-board power supply cannot be effectively raised.
The conventional on-board power supply assembly is still unable to meet the requirements to increase efficiency and power density, so there is a need of providing a power module assembly and an assembling method thereof to solve the problems such as heat dissipation of power devices, occupying area of power devices in the on-board power supply and installation method of the power devices.